Plaque Characterization of Carotid disease Predicting Outcome · Plaque Characterization of Carotid...

S

Plaque Characterization

of Carotid Disease

Predicting Outcome

Mark Wholey M.D. Medicall Director Peripheral and

Neurovascular , Highmark Allegheny Health Care

Network Adjunct Professor Engineering, CMU

Disclosure Statement of Financial Interest

• Grant/Research Support

• Consulting Fees/Honoraria

• Major Stock Shareholder/Equity

• Royalty Income

• Ownership/Founder

• Intellectual Property Rights

• Other Financial Benefit

• Abbott Vascular

• Covidien

• Setajon, North Wind

• Covidien

• North Wind

Within the past 12 months, I or my spouse/partner have had a financial

interest/arrangement or affiliation with the organization(s) listed below.

Affiliation/Financial Relationship Company

AT THE PRESENT TIME,

WE HAVE

LIMITED KNOWLEDGE

OF

PLAQUE CHARACTERISTICS

The goal is the search for the

elusive plaque before it becomes

symptomatic:

1. Identify vulnerable plaque and

TCFA

2. Prevent Plaque rupture

3. Avoid stroke

S

The reality

of

severe carotid

stenosis

The first symptom may be a

sudden permanent stroke

(25% of cases)

,

90% OF STROKES

35% of TIA

RUPTURE +

EROSIVE +

FRESH

thrombogenic

THROMBUS

10% erosive

ASYMPTO-

STROKE

MATIC

PRIOR

INTACT CAP

ORGANIZED

A

C

B

D

NC

F

Histopathology of Carotid Plaques

with different Clinical Presentation

Ranking of Vulnerable Plaque

S Whereas in terms of vulnerability the ranking,

based on postmortem data, might be different

with the CaTCFA being allegedly most high

risk plaque and FCa more stable

Considered as most

vulnerable plaque

Considered as least

vulnerable plaque

PIF FA CaFA TCFA CaTCFA FCa

Courtesy P. Margolis, MD

Significant Independent Predictors of

Non-Cluprit Lesions

1. Plaque Burden

2. TCFA by IVUS

3. Minimum lumen area

Presence of 2 or 3 of these predictors in

the coronary data have a 10-18% chance of

an event within 3 years

IVUS Indicates Pt Best Suited for CEA

A. B.

C. D.

Results OCT

Current Imaging Techniques

SEssentially all trials were

based on the Gold Standard

S Angiography

S Degree of Stenosis

The question is how do

we find these Stroke

indicators

There are 14 to 20 factors that influence CAS outcomes

Plaque morphology is only one, but it could be the one that will separate those patients best suited for surgery vs. stenting

Ipsilateral Lesions after CAS

transient weakness of right hand: TIA

Stent erosion of

Vulnerable Plaque

with rupture ??

Is vulnerable plaque the culprit in

procedural strokes?

The Problem MZ, 74y,

asymptomatic,

LICA stenosis 85%

SZ, 68y, asymptomatic,

LICA stenosis ~40% + ulcer

QCA 43%

Which of the two plaques should be treated by (CAS) or (CEA)?

MZ, 74y,

asymptomatic,

LICA stenosis 85%

SZ, 68y, asymptomatic,

LICA stenosis ~40% + ulcer

(in both – ‘full’ pharmacotherapy included ‘high-dose’ statin, ASA, ACEI)

Indication to CEA/CAS NO indication to CEA/CAS

MZ, 74y,

asymptomatic,

LICA stenosis 85%

SZ, 68y, asymptomatic,

LICA stenosis ~40% + ulcer

Indication to

CEA/CAS

NO indication to CEA/CAS

Motoric aphasia 4/5

Right hemiparesis 3/5

Patient selection

S 429 patients

S Male - 61.5% / Female - 38.5%

S Symptomatic (35%) and asymptomatic (65%)

S Symptomatic

S TIA, amaurosis fugax, or CVA with clinically, lateralizing

symptoms ≤ 60 days preceeding carotid intervention

Lesion Characteristics Based on

Angiography

S Length of lesion

S Percent stenosis

S Location of lesion (ostial vs. non-ostial)

S Ulceration

S Calcification

S Contralateral internal carotid occlusion

Carotid Stent Case

• 80 year old male with two days of right arm weakness

and brief expressive aphasia

• PMH quadraperesis secondary to remote cervical

fracture, previous trach, PEG

• Transferred from OSH with CTA showing high grade left

carotid stenosis

LEFT RIGHT

All flow from right side

RIGHT AP RIGHT lateral

VH in lesion( PIF)

PRE POST

6mm straight

stent 3 cm

long Exact

The Challenge: Identify Unique

Features Critical to Plaque Rupture

1. Plaque Burden

2. TCFA by IVUS, OCT, angioscopy, MRI-C

3. Lumen area (minimum)

OCT High resolution of fibrous cap thickness 10 x greater

than IVUS.

Plaque characterization;

Limitation – penetration lock 3mm.

Figure 2.

S

Necrotic Core

Without calcium

Fibrous Tissue

FibroAtheroma (FA)

Acute Plaque rupture with thrombosis may occur in non-

stenotic segment

What is optimal complete lesion coverage?

S Lack of clinical data

comparing method

S Impact on:

S Distal embolization

S Stent thrombosis

S Restenosis

S Plaque progression

Largest NC area

Angiography or IVUS-guided

VH-IVUS-guided

Stent may not expand

CTA Diag Angio

Carotid plaque

PRE

RIG

HT

Proton Density Weighted Images of the

Internal Carotid Artery at Baseline and after

12 months of Statin therapy

Outcomes of CAS Trials Over

Time

33 (Enrollment: 2000-2008) CREST – 5.7% (Enrollment: 2000-2008) CREST – 1.1%

Year 2000

Year 2008

SE2934600 Rev. A

Wallis de Vries, JVS 2008

Conclusion

Shower Emboli

Diffusion weighted

Should we avoid the aortic arch

Puncture with 21g

needle at C5 level

Bergeron

Technique for

direct carotid

access and

vertebral

For the vertebral use

radial or brachial

access

4 fr, sheath for carotid

Vertebal

from the

radial or

brachial

S

Complex type 3 arch

May be indication for direct

carotid access or radial for

vertebral basilar stroke

Too difficult from femoral

approach. 18% stroke

incidence from the aortic

arch

Archer Trial,2005

Remove wire, filter to internal carotid followed by pre dil and

stent

LUCAS, CARL

SCAFFOLDING AND CONFOMABLE

Percutaneous cervical approach and

closing for carotid artery stenting

Markatis et al 2009

N = 191

1637 patients European high volume experienced operator trial

OCT Reflected Infrared Light

Advantages

S Spatial resolution 10X >

than US

Disadvantages

S Displace blood with saline

S Limited penetration

S Cannot do entire vessel wall

Patient selection

S 429 patients

S Male - 61.5% / Female - 38.5%

S Symptomatic (35%) and asymptomatic (65%)

S Symptomatic

S TIA, amaurosis fugax, or CVA with clinically, lateralizing

symptoms ≤ 60 days preceeding carotid intervention

S

Conversely the 3 year event rate in

1650 IVUS patients was only .3%

and no events in the coronary artery

segment when plaque volume less

than 40% (Prospect)

THIS IS THE PROBLEM

IA (IVUS Defined) TCFAs

S

Major limitations in relying on

angiography for lesion

severity and plaque

composition

Lesion Length

(mm)

Peri-operative

CVA (%) 30 day CVA (%)

30 day Adverse

Event (%)

0 – 4.9 2.1 3.2 3.2

5 – 9.9 2.2 2.7 3.3

10 – 14.9 1.9 2.9 3.8

≥ 15 17.0 17.0 19.1

Lesion Length

P < 0.001 P = 0.002 P =0 .001

S

Anatomic and Lesion

characteristics are not

always accurate

predictors of Stroke for

CAS.

Which test is best for this?

This Is The Problem

ID (IVUS Defined) TCFAs

S

The reality

of

severe carotid

stenosis

The first symptom may be a

sudden permanent stroke

(25% of cases)

Hallett,J ,Veith

2010

S

All imaging modalities have

inherent limitations

S

Figure 1(A-F).

A.

B.

C.

D.

E. F.

Carotid plaques

PRE

RIG

HT

PRE

LE

FT

Representative Lesion Morphologies f (A) The earliest

atherosclerotic lesion, pathological intimal thickening, highlighted

by lipid pools (LP) in the deep intima (Movat pentachrome stain)

with CD68+ ...

VH IVUS Produces a color-coded map of 4

Histological Types

S dark green: fibrous

S yellow/green: fibrofatty

S white: calcified

S red: necrotic lipid core

plaque

Results (30-Day Follow-Up)

S Follow-up data were available on 56 (84%) of 67 patients in the CAS population.

S (2) major adverse events S Two immediate periprocedural strokes. S One patient (A) experienced a stroke in the

distribution of the PCA as shown on CT, likely related to arch manipulATION

S One stent thrombosis occurred, likely due to discontinuation of anticoagulation

S No strokes were reported in 2 of the 4 patients referred for CEA who were available at follow-up.

A

B

Conclusions

S Understanding plaque morphology is a crucial aspect in managing carotid occlusive disease.

S However, in this small sample population, stroke rates were not different than those reported elsewhere for carotid stenting. In these cases, VH IVUS did not offer insight into the possible causes of the events.

S Future studies are needed with prospective trials to evaluate CAS and patient outcomes correlated with VH IVUS findings.

Population CAS CEA

Male

Female

Age (years)

Side of ICA Lesion

Left

Right

Percent Stenosis

Clinical Indication

TIA

Amrous Fagux

Stroke

Asymptomatic

Prior CEA/Stent

Other

Unknown

41 (61%)

36 (39%)

73 ± 9.7

31 (46%)

36 (54%)

89% ±

7.8

5

2

5

24

10

13

8

2

2

84

3

1

85%

1

1

1

1

S CAS was performed in 65

of 71 patients

S Four patients were

excluded and referred for

CEA due to unfavorable

VH IVUS plaque

characteristics

S One patient was excluded

due to lack of significant

stenosis

S One patient underwent

PTA of a restenosed stent

Results

9%

24%

51%

76%

CAS Predominate

Plaque Characteristics

CEA Predominate

Plaque Characteristics

• 1 Necrotic Core/

Dystrophic Calcification

• 2 Dystropic Calcification

Adverse Events

S Two (3%) of the 59 patients undergoing CAS experienced adverse events. S One patient (A) suffered a minor stroke in

the perioperative period due to stent occlusion related to thrombosis due to discontinued anticoagulation.

S One minor stroke (B) in the perioperative period in the left posterior cerebral artery (PCA) distribution likely related to arch manipulation. Returned to baseline at 3 month follow-up.

A

B

Patient selection

S 429 patients

S Male - 61.5% / Female - 38.5%

S Symptomatic (35%) and asymptomatic (65%)

S Symptomatic

S TIA, amaurosis fugax, or CVA with clinically, lateralizing

symptoms ≤ 60 days preceeding carotid intervention

Lesion Characteristics

S Length of lesion highly significant

S Percent stenosis

S Location of lesion (ostial vs. non-ostial)

S Ulceration

S Calcification

S Contralateral internal carotid occlusion

Copyright ©2006 American Heart Association

Prabhakaran, S. et al. Stroke 2006;37:2696-2701

Plaque Surface Irregularity

Hazard Ratio 3.1

Ultrasound

S Computer assisted analysis suggested that

increased echolucency of plaque was a risk factor

during and immediately post stenting

Biasi, Circulation 2004

Acute Plaque rupture with

thrombosis may occur in non-

stenotic segment

Patient Selection

• 429 patients

• Male - 61.5% / Female - 38.5%

• Symptomatic (35%) and asymptomatic (65%)

• Symptomatic

• TIA, amaurosis fugax, or CVA with clinically, lateralizing

symptoms ≤ 60 days preceeding carotid intervention

What is Optimal Complete Lesion

Coverage?

• Lack of clinical data

comparing

S VH-IVUS guided vs.

angiography/conventional IVUS

guided PCI

• Impact on:

S Distal embolization

S Stent thrombosis

S Restenosis

S Plaque progression

Largest NC area

Angiography or IVUS-guided

VH-IVUS-guided

TYPE A Lesion

TYPE 4 ARCH

Procedure completed

FILTER REMOVED

Shower Emboli

Diffusion weighted

S

Presence of 2 or 3 of

these predictors have a

10-18% chance of an

event within 3 years

Acute Plaque rupture with

thrombosis may occur in non-

stenotic segment

TIP 5 - Continued

Figure 2.

S

67 Female with

TIA’s referred

for CEA; Path

reports soft,

atheromatous

lesion

Can Carotid CTA Characterize Plaque

Too High Risk For CAS? Dangerous:

Soft Plaque

Plaque Analysis: Are

These Necrotic Cores?

Both Patients referred for

CEA instead of CAS

CTA

S Arterial wall assessment of morphology is less impressive

than degrees of stenosis.

S Calcification is the only histologic content using CTA

Gao et al., Cerebrovasc Dis,

2009

•MRI with plaque rupture and intra plaque bleed

PLAQUE RUPTURE

TYPE A Lesion

TYPE 4 ARCH

Procedure completed

FILTER REMOVED

Shower Emboli

Diffusion weighted

Shower Emboli

Diffusion weighted

ADVANTAGES

S Procedure time

S Less contrast media

S No aortic arch manipulation

S No contralateral or vertebral embolisation

S

What have we

overlooked in the

neurovascular

evaluation The aortic arch as a source of vulnerable plaque whether diagnostic or

interventional procedures are being done

p

21 g needle at C5

Conclusions

Administration of lipid modulating agents appears to have initial paradoxical effects on lumen size:

A decrease in vessel wall area and lipid area is accompanied by a decrease in lumen area

An increase in vessel wall area and lipid area is accompanied by an increase in lumen area

Conclusion

S Percent stenosis provides relatively little information about vulnerability of de novo, statin-naive carotid plaques.

S As most current imaging studies concentrate on plaque stenosis, a more appropriate focus on plaque composition provides a more robust quantifiable volumetric metric and may be more indicative of the underlying pathology by high-resolution 3D CMR.

Carotid Plaque Analysis S Images were acquired in axial projection in a 2D and

3D manner

S via QPlaque (Medis, The Netherlands). Plaque morphology determined by T1, T2/PD CMR.

S Windows and level settings were set to constant levels to standardize signal intensities for each analyzed image.

S Manual contours identified: 1. Fibrous cap

2. Lipid pool

3. Outer and inner wall contours

4. T2 images were reviewed to determine/confirm lipid core determination with the T2 image used to confirm lumen contour.

– Fasting lipid profiles drawn on day of MR imaging

Current Imaging Techniques

S Essentially all trials were based on the Gold Standard

S Angiography S Degree of Stenosis

S

CAN IVUS FINDINGS

DURING CAS

PREDICT OUTCOME?

Carotid plaques

PRE PRE

LE

FT

Proton Density Weighted Images of the

Internal Carotid Artery at Baseline and after

12 months of Statin therapy

Wallace De Vries,JVS, 2008

AT THE PRESENT TIME,

WE HAVE

LIMITED KNOWLEDGE

OF

PLAQUE CHARACTERISTICS

Outcomes of CAS Trials Over

Time

• CAS results have vastly improved over time due to: (1)

more experienced operators; (2) better patient selection

and; (3) a wider spectrum of technology

• CAS outcomes have evolved over time similarly to CEA

PROBLEMS of the aortic

arch Complexities of the aortic arc are

responsible for almost all technical

failures

Ideal Trouble

More Trouble

S

Major limitations in relying

on angiography alone for

lesion severity and plaque

composition

S

All imaging modalities have

inherent limitations